Back from school on Thursday, Lulu was met at the door by Sonia Sofia Solinsky, who said to her, “We must hurry. Your parents return tomorrow night. Which means we haven’t much time for me to give you your final lesson in basic spy craft.”

She explained that this final lesson involved several clues that she had hidden all over the house, with each clue leading onward to the next. If Lulu succeeded in following them—which wouldn’t be easy to do—she would find, at the end, what the clues had been leading her to.

“Which is what?” Lulu asked. “Tell me, and I’ll get started. I’ll get started right now and be finished before bedtime.”

“I wouldn’t count on being done before bedtime,” said Ms. Solinsky. “And you aren’t permitted to know in advance what you’ll find. In fact, this particular lesson, which ends each set of my spy-craft lessons, is known as”—HERE IT COMES, FOLKS! HERE IT COMES!—“MM, which stands for”—YES!—“Mysterious Mission.”

(And that, I sincerely hope, takes care of that!)

MYSTERIOUS MISSION! Lulu totally loved it. And she knew without a doubt that she would succeed. Indeed, by now she was positive that she was the best spy-in-training that Sonia Sofia Solinsky—code name Triple S—had ever trained.

“Aren’t I the best spy-in-training that you have ever trained?” Lulu asked Ms. Solinsky.

“Let’s not get pushy,” Ms. Solinsky replied. Then she sat Lulu down in the kitchen, fed her an early supper, and handed her—printed neatly on a note card—the clue to where she should look for her next clue:

They have their ups.

They have their downs.

You do not like to use them.

This is the seventh one you’ve owned.

Because you always lose them.

Look inside it.

That’s where I decided

To hide it.

Lulu narrowed her eyes as she read and re-read and then re-re-read the clue. She read it to herself, and she read it out loud. After which she turned to Ms. Solinsky and asked, in a quite snippy tone of voice, “What kind of dopey, dumb, stupid clue is that?”

Good grief—has Lulu forgotten total obedience?

“Excuse me,” said Ms. Solinsky. “What did you say?”

Lulu, pulling herself together in the nick of time, replied, “Oh, I only just was saying that this clue is kind of confusing and was wondering if you could give me a little help.”

“Careful attention to each of the words,” Ms. Solinsky replied, “ought to give you all the help you need. And now I’m going up to my room and I don’t wish to be disturbed. You’re on your own.”

At the top of the stairs, however, Ms. Solinsky stopped for a moment. “Inside it. Decided. Hide it,” she said. “As you can see, my little spy-in-training, you’re not the only one who knows how to rhyme.”

You clever folks reading this story have doubtlessly already figured out what this clue was referring to. But it took Lulu quite a while to think of what goes up and down, and how she complains whenever her mom makes her use one, and that she had already lost a green one, a blue one, a plaid one, two flowered ones, and a frog one, making the yellow polka-dot one that hung in the front-hall closet her seventh . . . UMBRELLA.

Lulu rushed to that closet, reached inside the hanging umbrella, and found her next clue:

In something that rhymes with FOX

Is something that rhymes with EYES,

And taped to that second something is a clue.

You’ll discover it all by yourself

On something that rhymes with ELF,

And there’s even something for breakfast tomorrow too.

Two hours later, and getting close to her bedtime, Lulu came up—at last!—with BOX and PRIZE and SHELF and BREAKFAST CEREAL. Rummaging through the cereal boxes that stood on a shelf in the kitchen, she eventually pulled out of the Toasted Yummy Extra-Sugar Bits a purple plastic superhero—the prize—on the back of which was scotch-taped her next clue:

Inside of a shoe, near the toe,

Awaits what you next need to know.

This new clue, so short and simple, made Lulu wonder if Ms. Solinsky had run out of rhymes. Unless she’d gone soft and was giving Lulu a break.

But three hours later, and way way past her bedtime, Lulu had found no clue in the toe of a shoe, though she’d gone through every shoe in her closet, as well as every shoe of her mom’s and her dad’s, and had even checked out Ms. Solinsky’s combat boots. Disgusted, discouraged, and exhausted, she lay down on her bed to rest for a few minutes and discovered—when she slipped off her sneakers—guess what?

That’s right! She found a note card, neatly tucked into her left sneaker, near her big toe. And what we’d all like to know (and that includes me) is how, and also when, did that clue get in there?